Bomb release mechanism



E. w. CHAFEE ET AL. 75

BOMB RELEASE MECHANISM Feb. 10, 1948.

2 Sheets-Sheet 1 Original Filed Feb. 26, 1937 INVENTORS a EHEL W Cf/AFEE [lg V w/ TT NE Feb. 10, 1948. E. w. CHAFEE ET AL 2,435,575

BOMB RELEASE MECHANISM Original Filed Feb. 26, 1957 2 Sheets$heep 2 89 los INVENTORS Enzz. W CHAFEE h A 0 AN UKEN BY Patented Feb. 10, 1948 BOMB RELEASE MECHANISM Earl W. Chafee, Great Neck, and floward C. Van Auken, Manhasset, N. Y., assignors to The Sperry Corporation, a corporation of Delaware Original application February 26, 193 7, Serial No. 128,034. Divided and this application February 8, 1945, Serial No. 576,752

9 Claims.

This invention relates to an automatic bomb release mechanism and is a division of the application of Earl W. Chafee and Howard C. Van Auken, Serial No. 128,034, filed February 26, 1937, and now Patent No. 2,371,606,- issued March 20, 1945, relating to bomb sights.

An object of the invention is the provision of a simple releasing arrangement by which bombs may be accurately dropped upon a target.

Other objects of the invention will appear in the following description given with the aid of the accompanying drawings, of which Fig. 1 shows schematically a portion of the computing mechanism of a bomb sight;

Fig. 2 shows an arrangement for releasing bombs according to a preferred embodiment of the invention; and

Figs. 3 and 4 show details of a warning signal annunciator.

A portion of the bomb sight of the parent case, believed sufiicient for an understanding of the present invention, will now be briefly described.

Reflecting prism 2E! is adjustable about an axis 2| for the purpose of tracking a target. Adjustrnent is accomplished by bell crank 22 pivoted at 23 and provided at its lower end with a channel member 24 in which is positioned an arm 25 attached to the prism. The bell crank is turned on its pivot by a member 26 which engage the upper end thereof, the member being controlled by rod 2'! reciprocated by sight angle cam 2'5.

Spring 29 attached to the bell crank keeps the bell crank, member 28, rod 21 and cam 28 in en gagement.

In the computing mechanism shown, four a the course is level, a finger drops into a notch formed in the edge of a disc 52 secured to shaft 59.

When the course is not level, shaft 55 turns, but is otherwise stationary. The shaft, when in motion, is turned in proportion to the rate of change of altitude, and drives, through gears 55 and 51, a shaft 58 carrying long pinion 59 in mesh with gear 69 secured to cam 36, the long pinion serving to rotate cam 35 aswell as cam 3'5. However, when the course is level, it will be understood that these cams are stationary.

Lift pin SI of cam 35 translates cam 62, which is displaced in rotation by gear 63 secured thereto, the gear being in mesh with long pinion 64, driven by gears 55 from shaft 65 which turns in proportion to ground speed. Shaft 65 is driven, in the mechanism shown from the ground speed dial 61, by means of gear 68, shaft 69 and gears 10.

Cam 62 is also further displaced in translation with respect to lift pin 6! according to the ballistic coeflicient of different bombs to take care of the difference in time of fall thereof. This displacement is made by a knob 15 arranged to be set with respect to a scale 16. The knob is mounted on an extension of lift pin 6| which is threaded at H into an enlarged extension 18 from cam 62. Turning of knob 15 positions the cam axially on the lift pin extension.

three-dimension cams are used, of which cams V and 3b are supported by a shaft 31. Both cams are secured to a sleeve 38 which is free to turn on shaft 35 but is restrained from longitudinal movement thereonby fixed collars39 and t9. Shaft 2i! and the cams, thereon are translated according, to vertical velocity of glide by a rack 48 formed in the shaft which meshes with a gear 52 on shaft on which is secured another gear id meshing with gear t5 positioned by means of knob 45, shaft t1, and gear 48. Knob 56 is used to set the vertical velocity of glide into the sight and controls mechanism, not shown, which effects necessary adjustment of the sight when the airplane is not flying a level course.'

The knob is kept at a fixed position when the course is level by an arrangement including gear 39 on shaft 59 which meshe with gear G5. The shaft 5 is so positioned by the knob that when Cam 62 combines ground speed with a factor proportional to the time of fall of the bomb and also an altitude ratio so that its lift pin 19 is displaced according to whole range.

Lift pin 19 displaces a long lever which is also displaced by lift pin 8| of cam 82. The lever is used to operate one element of the novel bomb 'release mechanism of the present invention in accordance with the combined displacement of both lift pins which represents whole range less trail.

Cam 82' is translated by lift pin 83 of cam The inputs for the latter cam have been described, Cam 36 is laid out to translate cam 82 in proportion to the square of the time of fall (To) and the altitude ratio.

Cam 82 is positioned in rotation from shaft 85 according to a trail value. Cam 82 is so laid out as to displace its liftpin. 8| in accordance with the computed value of trail and this value is so modified by lift pin 19 that the left hand end of lever 89 is displaced in accordance with whole range corrected for trail.

Lever 88 is pivoted to a bar 89 slidably supported in a bracket 90, Fig. 2. A support 92 preferably of insulating material having an arm 93 attached thereto by pivot 94 is secured by screws 9| to bar 89. Spring 95 holds the arm against adjustable stop screw 99. A contact spring 91 is secured to one edge of the insulating support 92, while another contact 98 is attached to pivoted .arm 93 by a screw and nut 99. These contacts are moved with their supports in accordance with the relative displacements of lift pins I9 and 8|, and cooperate respectively with another set of contacts I and II, which are moved according to sighting angle. The operating mechanism for these contacts will now be described.

Shaft I is coupled to worm wheel I09 by slip clutch I01. Worm I08 is driven by means not shown efiective to turn wheel I06 and shaft I95 at a rate in proportion to ground speed, to a. position proportional to the tangent of the instantaneous sighting angle.

Gear I09 on shaft I05 meshes with a rack H0 formed on the edge of a slide III supported for parallel movement with respect to member 99 by uides H2 and H3.

A non-conducting bracket H5 secured to slide IH carries a contact block H6 to which is securedthe contact I00, which is so disposed thereon as to engage contact 91 at a predetermined relative position of member 89 and slide III. The bracket also supports contact IOI so disposed as-to make with contact 98 on arm 93 at a predetermined relative position of member 89 and slide I-II beyond the position at which contacts 9! and I00 are first closed. Contact I00 is elongated and once in engagement with contact 9'! will maintain sliding contact therewith while contacts 98 and I0I are moved towards each other until both sets of contacts are closed.

A contact strip H1 is engaged by a contact spring H9 supported by a bracket H9 fastened to guide H3. The contact spring is suitably insulated from the guide and is used to maintain a connection for the contacts held by bracket H5 with external circuits,-the connection in the present embodiment'being with one pole of a source of potential I25.

The contact arrangement just described may be used to operate a warning circuit and subsequently a bomb release circuit. In Fig. 2, contacts 91 and I 09, when closed, operate an annunciator device for giving a warning signal. In a preferred arrangement, a winding I29 of an annunciator has one terminal connected to a pole of the source of potential I25, and the other terminal connected through the tongue I21 and back contact I28 of a bomb release relay to contact 91. This circuit is completed to the opposite pole of the source of potential when contacts 91 and I00 engage, the circuit being through contact strip H1 and Wiper H8.

Winding I26 may operate a suitable armature arrangement for deflecting a warning flag I30 into the optical path of a sighting instrument where it will be observed by the bombardier. The details of a suitable arrangement of this kind are shown in Figs. 3 and 4.

Shortly after the warning signal, bomb release contacts 99 and -IOI close. These contacts control a bomb release circuit which is susceptible of numerous modifications, a preferred arrangement being shown in Fig. 2 where the winding I29 of a relay has one terminal connected to one pole of the source of potential I25, the other terminal of the winding being connected to the opposite pole on closure of contacts 98 and I'0I, the circuit including contact strip H1 and wiper H9.

When the winding I29 of the relay is energized, tongue I2! breaks with back contact I28, thus disconnecting the warning signal annunciator winding I29. Tongue I 21 then engages its front contact I32, thus effectively short-.circuiting contacts 99 and IOI.

If desired, an additional electromagnetic device such as is indicated by' reference character I33 may be operated directly by the circuits described for bomb release purposes. The device I33 is shown as being connected in parallel with winding I29 of the relay.

As the success of the bomb dropping operation depends largely upon the time at which the bomb is dropped, it is evident that it is very important to prevent the bomb dropping contacts from burning as that would be equivalent to a gradual change of their relative position. In the circuits disclosed herein, the contacts are protected by the arrangement which allows the contacts to close a circuit but prevents them from ever breaking a circuit, thereby eliminating destructive arcing at the contact points.

As the aircraft is approaching the target, contacts 9'! and I99 will eventually engage and close a circuit operating annunciator I26--I30. Next, contacts 99 and IM engage, operating the relay 5 29 and also the solenoid device I33 in accordance with one embodiment of the invention. The back contacts I21 and I28 of the relay break, deenergizing the warning signal. When front contacts I 21 and I92 make, they short-circuit bomb release contacts 99 and IN, and also establish a holding circuit for the relay through contacts 91 and I99 and the relay will remain operated as long as these contacts are closed. Contacts 91 and I99 are so arranged as to remain closed long after contacts 98 and MI have opened. With the further relative movement of member 99 and slide III, which may continue for some time, arm 93 will be turned in a counter-clockwise direction, initially by the engagement of contacts 99 and I 9i and later by the engagement of a roller I94 pivoted to arm 93 with insulating bracket H5, which separates contacts 98 and NH so that no appreciable sliding movement may occur therebetween to wear the contacts. At the time when the contacts 98 and IOI separate, they are short-circuited by relay contacts I21 and I32, and thus no arcing occurs.

During return of member 89 and slide III to their initial position, contacts 99 and IOI close again and later re-open, but while they are closed they remain bridged by contacts I21 and I32. With the arrangement described, it is possible to maintain the mechanical dimensions of the main contacts so that no appreciable change occurs therein after many operations, which would not be the case if the contacts were permitted to break the rather heavy current required for the operation of the circuits.

Since many changes could be made in the above construction and many apparently widely different embodiments of this invention could be made without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. In a bomb release mechanism for a bomb sight having a computing mechanism, a pair of members each movable independently under control of the computing mechanism in accordance with different computations, contact means so disposed on the respective members as to be brought into engagement at predetermined relative positions of the members, and electrical warning signal and bomb release circuits successively operated in the order named by the contact means.

2. In a bomb release mechanism for a bomb sight having a computing mechanism, a pair of members disposed for parallel movement, means for moving the members independently under control of the computing mechanism in accordance with different computations thereof, contact means comprising a plurality of sets of independent contacts disposed so as to be successively actuated by the members at predetermined positions thereof, an electrical warning circuit controlled by a first operated set of said contacts and an electrical bomb release circuit controlled by a subsequently operated set of said contacts.

3. In a bomb release mechanism for a bomb sight having a computing mechanism, a pair of members disposed for relative parallel movement under control of the computing mechanism, contact means comprising a plurality of sets of independent contacts disposed so as to be successively actuated by the members at predetermined positions thereof, an electrical warning circuit controlled by a first operated set of said contacts, a bomb release circuit including a relay controlled by a subsequently operated set of said contacts, and means for connecting a protective shunt about the last-mentioned contacts controlled by the relay.

4. In a bomb release mechanism for a bomb sight having a computing mechanism, warning contact means, bomb release contact means, means controlled by the computing mechanism for operating the contact means successively in the order named, an annunciator device, an operating circuit therefor controlled by the warning contact means, and a relay controlled by the bomb release contact means having contacts interconnected in said operating circuit adapted to disable the annunciator device. 7

5. In a bomb release mechanism for a bomb sight having a computing mechanism, warning contact means and bomb release contact means controlled by the computing mechanism successively in the order named, a relay controlled by the bomb release contact means, and contact means controlled by the relay when operated for connecting a protective shunt across the bomb release contact means.

6. In a bomb release mechanism for a computing bomb sight having a computing mechanism, warning contact means and bomb release contact means controlled by the computing mechanism of the bomb sight successively in the order named, an annunciator circuit controlled by the warning contact means, a relay controlled by the bomb release contact means, relay contacts and circuit means connected thereto efiective when operated to disable the annunciator circuit and to connect a protective shunt across the bomb release contact means, and other circuit means including said warning contact means for holding the relay when once operated in operated condition independently of the bomb release contact means.

7. In a bomb release mechanism for a bomb sight having a computing mechanism, warning contact means, a warning circuit controlled there by, bomb release contact means, bomb release circuit means controlled thereby, means controlled by the computing mechanism according to the computations thereof for first closing the warning contacts and then closing after a predetermined interval the bomb release contact means, and means controlled by the bomb release circuit on the closing of the bomb release contact means for disabling the warning circuit and thereafter shunting the bomb release contact means to protect the latter.

8. A bomb release mechanism for a bomb sight, including a warning relay, a transfer relay, a bomb release relay, a relatively movable pair of normally open warning contacts adapted on movement from a neutral position to engage and to energize thereby said warning relay at a given time interval before dropping the bomb, a relatively movable pair of release contacts, circuits controlled thereby adapted to energize said bomb release relay and said transfer relay in parallel, multiple switch means operated by said transfer relay, circuits controlled thereby adapted on the operation thereof to simultaneously deenergize said warning relay and to short-circuit said release contacts, and to electrically lock said release relay and said transfer relay, said warning contacts, upon being separated during the return to tgheir neutral position, breaking said electrical loc 9. In a bomb release mechanism for a bomb sight, a bomb release circuit, a first pair of relatively movable contacts controlled by the bomb sight, means brought into action by said contacts on engagement thereof to give a timed warning signal, a second pair of movable contacts controlled by the bomb sight adapted on engagement to make but not to break a bomb release circuit, means in said circuit and operated by said contacts to cause release of the bomb, and a second means in said circuit to cause interruption of said warning signal and to simultaneously transfer control of said circuit from said second pair of contacts to said first pair of contacts.

EARL W. CHAFEE. HOWARD C. VAN AUKEN. 

